How effective is optimization for conversions?

Hi Guys...

I have mostly just used Link Clicks or Clicks (deprecated now) as the optimization for ad delivery.. But lately performance on new ads has been complete shit with ridiculous CPCs... I tried Daily Unique Reach and Impressions before but the CTRs drop and CPCs shoot up

I've always been paranoid with using FB's pixel for Conversions but I think its time to make the leap...

For those of you that have tried it, how effective is it?

Does optimization for Conversions usually outperform Link Clicks?